The invention relates to an apparatus for removing break-out portions and in particular waste pieces from a sheet of material which contains blanks or the like and which rests on a break-out surface in such a way that the break-out portion extends over an aperture in the break-out surface and is pressed downwardly through the aperture under the pressure of at least one break-out member, in particular a break-out pin, wherein associated with the break-out member beneath the break-out portion is a support which is guided in the direction of movement of the break-out member.
For more than thirty years automatic stamping machines for producing blanks from sheets of cardboard in the folding box industry have been provided with break-out devices which are preferably disposed in a setting-up table outside the stamping machine. Such a break-out station is of particular significance from the point of view of the production operation as, if it is used incorrectly, it takes the greatest proportion of the total setting-up time and a poorly adjusted break-out station results in continuous disturbances in the production procedure.
In the break-out station, after the stamped sheet of cardboard reaches a predetermined retaining position on the break-out surface which is usually provided by a break-out board or die, the waste piece or pieces is removed from the stamped sheet of cardboard by means of break-out pins or cutting edges which press against the cardboard from above.
In the development of the break-out technology, there was first the upper tool pin which presses downwardly and which passes the waste piece through the aperture in the break-out board. The next stage in development added an additional lower tool with lower pins which align with the upper tool pins and which hold the waste piece in position with a clamping effect. As a break-out tool can reliably break out a waste piece only when there is a certain degree of engagement between the tool and the waste piece, the above-indicated lower pins have proven to provide an advantageous resistance at the moment at which the break-out tool or member encounters the waste piece to be broken out.
If the use of a clamping tool is to be avoided, the break-out aperture in the break-out surface at various locations thereon must be kept smaller than the waste piece associated with the respective aperture so that the waste piece lies with a high level of friction on the break-out surface or die, in contact therewith over small surface portions. The resistance now occurs when the break-out pin encounters the waste piece, by virtue of the friction produced. When the break-out pin and the waste portion pass through the aperture, a friction effect occurs at the narrower walls of the hole or aperture, thus producing a certain level of frictional engagement.
Also known is the so-called DYN-pin, being a break-out pin with a tip having substantially conical side walls which have concave contours in cross-section. In the break-out process, the tip of the pin encounters the waste piece which, by virtue of the waste piece being supported against the edges of the aperture, opposes so much resistance to the tip of the break-out pin that the tip can penetrate slightly into the material of the waste piece. That prevents undesired lateral deviation of the waste piece.
When it passes through the aperture, the waste piece bends; the stress between the waste piece and the wall of the aperture presents the DYN-pin with sufficient friction to provide the desired frictional engagement with the waste piece; that possibly makes it unnecessary to provide a bottom tool, per se, when using the DYN-pin.